It is interesting how certain artists in time, con­sciously or unconsciously, come to hold a sort of visual patent. This can be a specific choice of mate­rials, a conceptual strategy or a colour, such as Yves Klein's actually patented blue. Generally, we have to make do with watermarks, in the form of textures, gestures and impersonal fingerprints. In the Nordic countries, we have two “concrete extremists,” who both convincingly have cut to the core of visual research‑Sweden's Olle Baertling, with his trademark diagonal, and in Denmark, lb Geertsen, who with equal consistency has managed to embrace two of the basic shapes, merging irreconcilables by giving the square round corners or augmenting the circle with a square corner. With great generosity, these “mod­ernist mutants” are strewn across paintings, they assume stabilizing positions in refined mobile con­structions or act as holes in concrete sculptures, big enough to crawl through. Actually, this fusion of circle and square ought to be as universal as our relationship to the basic shapes, if nothing else then as a challenge to our inbred urge for logic.